Whooping cranes' predatory behavior key for adaptation, survival

A few cranes are looking for frogs and snakes in Louisiana. Credit: Vladimir Dinets

The whooping crane, with its snowy white plumage and trumpeting call, is one of the most beloved American birds, and one of the most endangered. As captive-raised cranes are re-introduced in Louisiana, they are gaining a new descriptor: natural killer.

A new study from the University of Tennessee, Knoxville, suggests Louisiana cranes are faring well thanks in part to their penchant for hunting reptiles and amphibians.

Until now, mostly anecdotal evidence existed that whooping cranes regularly hunt reptiles and amphibians. Their natural history is insufficiently known, despite years of research.

Vladimir Dinets, a UT assistant professor of psychology, observed whooping cranes while participating in a reintroduction project in Louisiana, where these birds are being released after decades of absence. Since little natural habitat remains there, the captive-raised birds have to adapt to an agricultural landscape.

Dinets' study showed that reptiles and amphibians are an important high-value food source for the reintroduced whooping cranes, particularly in spring nesting season. Previously, some observers considered reptiles and amphibians to be only occasional prey of whooping cranes.

The findings were published recently in the American Midland Naturalist.

Dinets found that the cranes regularly hunted frogs and snakes, and also occasionally took lizards and baby turtles. In early spring, some cranes would even enter forests to feast on tadpoles and froglets in temporal pools. In late spring, when countless reptiles were basking on the edges of rice fields and crayfish ponds, the cranes spent a lot of time looking for them.

"Spring is a critical time for the cranes because it's the nesting season," Dinets said. "Having such an important source of protein might be exactly what they need to survive in the world forever changed by human activities."

The whooping cranes' predatory behavior indicates they have an increased chance for survival. In other parts of the range the birds' food is dependent on what is available, including seeds, tubers, acorns, crayfish and insects.

"The cranes' behavior also shows that they are very adaptable in general, being able to use a broad variety of resources," Dinets said.

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